The present invention relates to a sampling system for use with water quality sensors used for monitoring the quality of water being treated in water purification or sewage treatment plants.
A sampling system for use with water quality sensors is currently used in water purification or sewage treatment plants because (1) it facilitates the maintenance and management of the sensors, (2) the construction of the sensors requires it, and (3) great economy is realized by measuring the quality of water at many points using a single sensor. An example of a conventional sampling system is shown in FIG. 1, wherein the numeral 1 indicates a sampling port, 2 is a sampling pump, 3 is a sensor, 7 is a cleaning water tank, 6 and 7 are both automatic pipe cleaner elements, 8 is a sampling pump motor control center, and 9 and 10 are each drain pits. The automatic pipe cleaner 6 consists of a pipe cleaning ball supplier 6a, cleaning control valves 6b, 6c and 6d, and a cleaning control panel 6e, whereas the cleaner 7 consists of a ball collector 7a and cleaning control valves 7b and 7c. Water sampled at port 1 with pump 2 is directed to sensor 3 through valve 7b, ball collector 7a and valve 6b, and is thereafter discharged into pit 10. In this sampling mode, cleaning valves 6c, 6d and 7b are closed. In a pipe cleaning mode, sampling pump 2 is first stopped and cleaning pump 5 is actuated. At the sample time, cleaning valves, 6c and 7b are opened, and the cleaning water in tank 4 is directed through pump 5, valve 6c, ball supplier 6a, ball collector 7a and valve 7b and is discharged into pit 9. In this cleaning mode, pipe cleaning balls are delivered from supplier 6a and as they are carried along by the cleaning water travelling to ball collector 7a, the balls clean the intermediate piping. Valve 6a controls the flow of the cleaning water and directs any returning flow to pit 10. The sequence of the above steps is controlled by control panel 6e and control center 8.
The conventional sampling system has the following defects: (1) the balls must be supplied and collected manually; (2) cleaning with the balls is possible only when the piping has smooth inner walls, and (3) the balls cannot pass through the sensor, valves and the piping around it, the sampling pump or sampling port, so these areas cannot be cleaned with the balls. For these reasons, much labor is needed in cleaning operations and frequent periodical cleaning is necessary.